Re: [ccp4bb] twwining operator

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: Molecular Replacement of a Known Anomalous Substructure
From: "Murray, James W" j {- dot -} w {- dot -} murray {- at -} IMPERIAL {- dot -} AC {- dot -} UK
Date: 2007-05-22

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Subject: Re: CNS problem: anneal.inp segmentation fault
From: jean jean {- at -} SCIENCE {- dot -} UCT {- dot -} AC {- dot -} ZA
Date: 2007-05-22

Subject: Re: twwining operator
From: James Irving irving {- dot -} james {- at -} GMAIL {- dot -} COM
Date: 2007-05-22

Hi Siva,

SFCHECK (part of CCP4i) has a very handy option for this. From the
command line:

% mkdir mydir
% sfcheck -f mydata.mtz -po mydir/ -out u -r
% gv mydir/sfcheck_XXXX.ps
(or ghostscript/xpsview/whatever postscript viewer you have)

This will generate a number of output files, including a useful
postscript summary of your data (including twinning operator and
fraction, if detected). If twinning is detected sfcheck will also
output a detwinned dataset (sfcheck.hkl) which is in CIF format -
although at least with my version before you convert the CIF to MTZ in
CCP4i, you have to change the line in the .hkl file that reads
"_refln.F_meas_au_sigma" to "_refln.F_meas_sigma_au".

However, unless your twinning fraction is low and your data behaves well
under detwinning, I would suggest using the twinned data as is, in
SHELX, CNS or PHENIX.

Best of luck,
James

siva charan wrote:
> hello
>
> I have a data set to 2.4 A, which has space group of *P21 *. From the
> cumulative intensity distribution graph, indicates that data is
> twinned . To run the detwin program in ccp4, one has to know the
> twinning operator. Can anybody help me, how can I get the twinning
> operator for monoclinic space group. I have checked for twin operators
> at http://www.ccp4.ac.uk/dist/html/twinning.html, but there are no
> twining operators for monoclinic space group.
> regards
> siva
>

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Next message:
Subject: Re: CNS problem: anneal.inp segmentation fault
From: jean jean {- at -} SCIENCE {- dot -} UCT {- dot -} AC {- dot -} ZA
Date: 2007-05-22